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A few small issues....
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Author:  Jsyphil [ Tue Apr 21, 2015 6:37 am ]
Post subject:  A few small issues....
My 238 Vista is back in the water, looking great and 99% sorted now, but i have a few small issues.
Want to get sorted soon as the weather has started to get nice!!
Before i pay someone to have a look for me, i thought i'd ask the wise of this forum if they've any ideas!

To summarise:
Volvo Penta 4.3Gi engine, Throttle body injection. New Long block in 2008.

This year, i've changed the HP Fuel pump, cleaned out the Vapour Seperator Tank as the water hoses were clogged and there was dirt inside.
With the service i did, early in the year i've changed Plugs, Distributor Cap/Rotor Arm, Oil Filter, Oil, Fuel/Water Seperator.

Engine starts and idles ok, although is overfuelling. Black smoke and unburnt fuel smell. Doesn't matter if cold, or warm, it always overfuels. The plugs are black too, although all are dry when removed after. Always starts/runs easy, just lots of black smoke!! idles at 5-600RPM (Where it should).

Taken out to sea, it accelerates well onto the plane at 2800/3000 ish RPM indicated. (18-21kts ish) Engine sounds smooth and is responsive - BUT Won't accelerate over 3200RPM, just bogs down, almost like a limiter or when the intake is restricted. No backfiring/popping, just bogs down and won't go any further towards WOT which is listed as 4500 - 4800RPM for my engine.

I've tested the ECT resistance cold and hot with boiling water and it seems to be working ok, with the resistance Increasing/Decreasing as it should.

No Fault codes registered either, just flashes code 12 like it should when tested.

I do think it's a fuelling issue, rather than Ignition - but will change the leads with spares that i have to check. The one thing i haven't done is check Fuel pressure, as i don't have the equipment.

Before i take it in, anyone any ideas please???

Cheers for now

Phil

8)
Author:  Graham R [ Tue Apr 21, 2015 4:32 pm ]
Post subject:  Re: A few small issues....
Someone had a similar problem a few years ago with his 238 ( member "Beyondtheblue" and a 5.0Gi if I remember right). It was the injectors in the TBI unit ( there are 2, the same as in the automotive TBI assemblies at least they were on his 5.0, so he didn't have to pay VP/ marine prices))
Author:  Winter Sux [ Tue Apr 21, 2015 6:14 pm ]
Post subject:  Re: A few small issues....
Agreed. Sounds like a bad injector. A quick and easy test; with a timing light, hook it up like you're checking the timing but direct the light closely at the spray patterns. It will appear to freeze the spray patterns and you will be able to see if one of the two is over-injecting.

In the trade, this is exactly how we check for flooding or starving TBI injectors. Even if this doesn't reveal your problem, it's really cool to see. Play with the throttle as well. It's a nice show.
Author:  deafwish [ Tue Apr 21, 2015 6:15 pm ]
Post subject:  Re: A few small issues....
Does it run an AIT (air intake temp') switch?
Many ECU's will add additional fuel during cold starts & may continuously be doing so if the switch is not connected/ faulty.
Just a thought... :wink:
Author:  LouC [ Tue Apr 21, 2015 7:16 pm ]
Post subject:  Re: A few small issues....
Do these engines use a temp sensor to determine if it runs in enrichment mode? If so can you test the resistance of it under cold and hot conditions? I have never had an EFI boat so I don't know how it enriches the fuel for cold start and cold running, but most EFI systems use a coolant temp sensor.
Author:  TX H210SS [ Wed Apr 22, 2015 1:43 am ]
Post subject:  Re: A few small issues....
My model has a fuel regulator valve...mine was stopped up which restricted flow, but don't know if it could cause over fueling. Auto Zone here let's you use a pressure test kit for free...50 dollar deposit but they return it. It was easy to use
Author:  Jsyphil [ Wed Apr 22, 2015 2:12 am ]
Post subject:  Re: A few small issues....
Thanks Guys, I really appreciate the thoughts/ideas.

Graham R/ Winter Sux, i have a Timing gun so will have a play tonight/tomorrow and look at the injector patterns. I know they're both firing, but haven't paid much attention to cones/patterns/flows etc so will check this out. Would faulty injector(s) be able to cause both of my issues?? Ie. Rich at Idle and lean at higher revs??

Deafwish/Lou - Mine runs a Coolant Temperature sensor to determine fuel enrichment at idle. This was the first thing i tested as it's a common failure item - but in boiling water the resistance moves as it should and vica versa when it gets cold, so i'm sure this is working as it should.

TX - yes mate, i will have to get the fuel pressures checked i think. There is a regulator in the TBI unit but i don't think it's adjustable/serviceable....

I will remove both injectors to check screens etc. and then get the timing gun out - will let you all know how i get on. Oh for the relative ease of a carburettor. I'd have had this sorted by now....!! :roll:

Cheers guys, really appreciated.
Author:  LouC [ Wed Apr 22, 2015 3:39 pm ]
Post subject:  Re: A few small issues....
I wish I could help more as I have only had the old '88 OMC with the 60s vintage Rochester Quadrajet 4 barrel carb. These are pretty complex carbs to rebuild, not simple like the Autolite 2100 I had on my '70 Ford 302 V8 but when they are set up right they work very well. They were pretty much a standard item on our old school Detroit Iron from 1965-1983 or so when throttle body injection (which is what you have) took over.
Other things...make sure there are no vaccum leaks, check all the terminals and connectors for corrosion, make sure that wherever the control unit is supposed to be grounded, it has a good clean ground. On boats that sit in damp climates all winter (and Long Island in winter is probably just as damp as the UK, but with more snow lol) you can find oxidation and mild corrosion in all kinds of places that cause excessive resistance. I had to replace all the old style glass fuses for that reason. All the battery wiring I changed years ago. And I had to re-terminate all the starter wiring because of corrosion (salt water caused, by a leak from the ex manifold drain right above the starter).
Author:  Graham R [ Wed Apr 22, 2015 4:16 pm ]
Post subject:  Re: A few small issues....
Who was that genius at VP that designed the exhaust manifold drain to pour water onto the starter and ground connections ? That person is now probably a VP ( edit; an inadvertent pun !)
Author:  LouC [ Wed Apr 22, 2015 4:56 pm ]
Post subject:  Re: A few small issues....
Well on mine (OMC Cobra) I can't blame Volvo lol. I do appreciate being able to use these one piece manifold/riser units with no joint to leak. My solution is to put a bit of OMC gasket sealer on all the drain plugs.
Author:  Technologic80 [ Mon Apr 27, 2015 9:14 am ]
Post subject:  Re: A few small issues....
As somebody with twin 4.3Gi engines, never underestimate the low or high pressure fuel pumps as culprits - 1 low pressure pump was bad on my port engine, and 1 high pressure pump was bad on my stbd engine and it took me 2 years of throwing parts/diagnosing to find it out $$$$$. The problems I was having just didnt seem like fuel pump problems. I swore it was ignition related or something else.

The fuel pumps worked - as in, when you turned the key they buzzed and primed, however they were NOT pressurizing the system enough. I had a myriad of strange driveability problems that almost drove me into a straight jacket!
Author:  Jsyphil [ Tue Apr 28, 2015 8:32 am ]
Post subject:  Re: A few small issues....
Technologic80 wrote:
As somebody with twin 4.3Gi engines, never underestimate the low or high pressure fuel pumps as culprits - 1 low pressure pump was bad on my port engine, and 1 high pressure pump was bad on my stbd engine and it took me 2 years of throwing parts/diagnosing to find it out $$$$$. The problems I was having just didnt seem like fuel pump problems. I swore it was ignition related or something else.

The fuel pumps worked - as in, when you turned the key they buzzed and primed, however they were NOT pressurizing the system enough. I had a myriad of strange driveability problems that almost drove me into a straight jacket!


Thanks - if you could post me that straightjacket, i'll need it soon i think! :lol:

HP Fuel pump has been changed with a new unit in December, but i agree and you're right, it most certainly could be a fuelling issue. It's definitely overfuelling, worse now than it used to be. I started it at the weekend and after running for 10-15 mins and shutting off there was Petrol on the water behind the boat... :?
It's not as smooth as it was and there's still the black smoke/rev problem.

Anyhow, the weather has started to get better now, i'm away in London this weekend so have asked someone to look at it for me early next week. I haven't really got the time to keep messing around and not getting anywhere. If i knew what was wrong i'd be able to fix it, but i'm chasing my tail trying to diagnose exactly what my issues are.

Hopefully by next week i'll know what's going on, hopefully it's nothing really serious. At the very least like i say, if i know what's wrong i'll be able to sort - the guy i use i've had a good chat with and he's happy to diagnose the issues for me.

I will let you know what happens next week......
Author:  Jsyphil [ Fri May 15, 2015 9:47 am ]
Post subject:  Re: A few small issues....
Right, some info.

My friendly mechanic spent a few hours today on it.

Compression tested ok, ignition all ok. No fault codes.

AICV wasn't working, but now is. Changed plugs to OEM Volvo Penta as the NGK ones i'd been supplied were incorrect heat.

Runs better (I'm told) but still overfuelling.
He tested Fuel Pressure and the HP Pump is overpressurising the system, he reckons - which would explain the fuelling issues.

So. Fuel Pressure Regulator seems to be the culprit.
Will have to see if the Diagphram/spring is available as a spare, i guess. If not, have i any other options, does anyone know? (GM/Car spare etc?)

Fingers crossed. 8)
Author:  LouC [ Fri May 15, 2015 11:20 am ]
Post subject:  Re: A few small issues....
What Volvo model # or year is the engine package?
Author:  Jsyphil [ Fri May 15, 2015 11:28 am ]
Post subject:  Re: A few small issues....
Hi Lou,

It's a Volvo Penta 4.3Gi PWTR year 2000.

Cheers

Phil
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